Heat conducting tube



Feb. 4, 1936.

T. E. MURRAY HEAT CONDUCT I NG TUBE Original Filed May 23, 1924 ase okPatented Feb. 4, 1936 HEAT CONDUCTING TUBE Thomas E. Murray, deceased,late of Brooklyn, N. Y., by John F. Murray, Joseph B. Murray, and ThomasE. Murray, Jr., executors, Brooklyn, N. Y., assignors to MetropolitanEngineering Company, a corporaton of New York Original application May23, 1924, Serial No. '715,369. Diviled and this application July 15,1931, Serial No. 550,903

18 Claims. (Ci. 257-262) In a previous application No. '715,369, filedMay 23, 1924 Patent No. 1,844,407, February 2, 1932, there is describeda wall for boilers or heaters and a tubular unit adapted to be usedtherein 5 having a fiange or fianges extending lengthwise thereof so asto provide a heating surface exposed to the heating gases greater thanthe surface which is in contact with the water or other fluid in thetube. The present application is a di- 10 Vision thereof. Theaccompanying drawing illustrates embodiments of the invention.

Figs. l and 2 are respectively a horizontal section and an upper part ofan inside elevation of the side wall of a boiler built with the tubular13 units of the invention.

Fig. 3 is a diagram illustrating a method of production of the fiangedtubes.

Figs. 4, 5, and 6 are plans of various forms of unit made in accordancewith the invention.

: Fig. 7 is a side elevation of the upper end of one oi the units.

Referring to Fig. 1, the boiler wall is made with an inner lining orscreen comprising tubes l with lateral flanges 2 extending across thespaces between the tubes and overlapping each other so as to form abaiiie between them. On the outside of this screen is the wall of theboilerstructure which may be of any usual or suitable mae terial andwhich as illustrated comprises refractory blocks or bricks 3 outside ofwhich are tiles 4 of non-conducting material and an outer shell 5 ofsheet metal. The longitudinal fins extend throughout such portions ofthe length of the tubes as may be desired according to the design of theboiler and preferably throughout the zone of radiant heat where theirconducting efiect is of greatest value. As shown in Fig. 2, they ex-`tend-substantially up to a header 6 into which the upper ends of thetubes are introduced, leav- .V:: ing the tubes without flanges for asufiicient length to facilitate the making of the joints with theheader. The fianges may extend clear down to a similar' header below; ormay be omitted at the lower end where their cooling efiect on the .13fire bed might be objectionable as illustrated, for example, in theapplication No. 678,443 filed December' 4, 1923 now Patent 1,953,768 ofApril 3, 1934 and illustrating a boiler wall made with such tubes.

50 The ns on the tubes serve to transmit heat to the tubes and the wateror other fluid therein, and also to protect the masonry or other backingof the wall from the heat oi the fiame. There is.naturally aconsiderable expansion of the metal p by the heat and it varies atdifferent points in 5 the wall. The fianges therefore, while theypreferably close the spaces between the tubes by overlapping at theiredges, are not Secured together but are free to permit relative movementand also to facilitate the repair of the wall in case 10 one or more ofthe tubes or flanges may be damaged. To conduct the heat moreeificiently to the tubes, and to prevent their partial separation fromthe tubes under the distortion produced by the high temperature, theanges should make as strong a connection as possible to the tubes andthe area of the connection should be fully equal to the section of theanges. For this purpose I propose to weld the edges to the tubes and toprovide a welded area at least equal to and preferably greater than thatof the long'- tudinal section of the fianges.

In Fig. 3 there is illustrated a suitable method of butt-welding asimple lange using the flash welding method or the method described inthe Murray Reissue Patent No. 15,466 of October 10, 1922 in which acurrent of extremely high ampere strength for a very brief regulatedperiod of time is passed through substantially the entire surfaces incontact while the parts are pressed together. The tube l is clampedbetween a pair of positive electrodes IO. The plate 2 is clamped intonegative electrodes l I. The plate has its edge which is in contact withthe tube slightly beveled. The weldingcurrent is passed as explained andthe parts are welded flrmly with a take-up sufficient to bring the jointto a greater thickness than that ofthe plate, as shown at 'I in Fig. 4.

Figs. 4 to 6 show a single ange on each tube, 40 and the invention maybe applied in this way With the single ange arranged to extend over allor any desired part of the space between two tubes. But, for a givenspacing of the tubes, a flange on each side is preferable since it doesnot have to be so wide as a single fiange would and since it provides ashorter distance for conduction of heat through the fiange to the tube.Also, instead of making the anges as in Fig. 1 so wide as to overlap,they may be made of less width and arranged to contact or even to leavea space between their adjacent edges. Also, besides the side flangesillustrated, there may be one or more fianges arranged along the frontof each tube, that is, the side of it which is exposed to the furnacegases in order to provide a larger heating surface; and one or morefianges arranged at the back of each tube for connection to the outerpart of the wall and for other purposes.

The Construction above described is covered in application No. '715,369,now Patent 1,844,407 above referred to. According to the presentapplication the fianges, or one or more of them where a plurality offlanges is employed, are interrupted at intervals in their length. Thisis particularly advantageous for units of considerable length such asare required in modern high duty boilers, for example. The interruptedconstruction serves a greater convenience in application of the fiangeto the tube and is particularly important in that it permits distortionof i the units without excessive strain on the welded joints.

The fianges-may be of various shapes in cross section. There are a`number of standard rolled shapes which are suitable, several of whichare illustrated in the aforesaid application No. '715,369 now Patentl,844,407. There are numerous others that are available.

In Fig. 4, the fiange is a common rolled bar or strip of rectangularcross-section and of about the same thickness as the tubeand is unitedby butt-welding at the joint 1. In the welding operation the root areamay be increased as shown. The tube is assumed to be ordinary seamlessboiler tubing. In Fig. 5, the fiange 8 is made of a bar tapered incross-section with its wider edge butt-welded at sa. This isadvantageous in that theincreased width 'tends to compensate for theincreased amount of heat that the plate must carry as it approaches thetube and gives greater resistance against sidewise distortion strains atthe joint.

In Fig. 6 the fiange 2 is made of a bar similar to that in Fig. 4.Instead of butt-welding, however, the are-welding method is applied tothe joint. Metal 9 is deposited by the electric arc and welded to thefiange and to the tube over* areas which are at least equal to thelongitudinal section of the fiange and preferably greater to allow forany imperfections. This figure may be taken to illustrate also abutt-weld 'I as in Figs. 4 and 5, supplemented by the arc-welds 9.

A single tube may be used in making up each of considerable length andof comparatively small diameter, the length being measured in feet andthe outer diameter being a few inches, 3 to 5 inches in. largeinstallations. The wall thickness is slight compared with the diameterso as to eifect a rapid transfer of heat.

The drawing illustrates tubes with a wall thickness about one-twelfth ofthe diameter. In prac-. tice boiler tubes are made even thinner.Standard 4-inch boiler tubes have a wall thickness of .structed as topreserve the original strength and tightness of the tube against leakageunder the prevailing conditions of internal pressure. With this aim, theconstruction is such as to maintain the wall of the tube intact.

The fiange is a separate rolled strip or shape which does not involveany break in the continuity of the wall of the tube. The inner edge ofthe fiange member is abutted against the continuous outer surface of thetube. The desired wall thickness is not reduced at any portion of itscircumference.

The flanges may be made of ordinary rolled steel. But where they are tobe subjected to very high temperatures it is advantageous to use a metalwhich is better adapted to resist deterioration by ox'idation at suchtemperatures. A number of such metals are known, largely alloys of ironwith nickel, chromium and the like. There are also known methods ofproviding a surface or skin on steel which will resist oxidation,generally by impregnating the surface of the steel with some other metalor alloy. A good example of such a process is that known commercially ascalorizing, in which the`surface of the steel is given a thin butcontinuous and very adherent toward the root roughly in proporton to itswidth in order to theoretically take care of the quantity of heat to beconducted. The actual extent and rate of such increase in thicknesswould vary with different conditions.

In some locations, particularly where the tube is to be embedded orotherwise firmly held, it is important to guard against bucklng orsimilar distortion owing' to the difference in the heating effect on theremote edge of the fiange and also on the cooler wall of the tube. Ithas also been found that in the operation of welding serious strains areset up in the completed unit which tend to warp it in use and even tobreak or crack the wall of the tube. A 20 foot tube has been found tosufier a decrease of approximately a quarter of an inch in its length inthe welding' of a continuous fiange thereto. By making the fiange inseparate short pieces the strain is lessened and is distributed evenlythroughout the i length of the tube, both in the production and in theuse of it.

According to the present invention these dilculties are avoided byinterrupting the fiange at intervals in its length; Fig. 7 shows thefiange 2, interrupted at intervals in its length by short spaces !2,extending all the way to the tube. Or such separation of the adjacentparts of the fiange may exist for a part of its width, extending inwardfrom the edge sufliciently to meet the circumstances. Each of theflanges or pieces 2 may be of any of the shapes in cross-section abovereferred to and may be applied by any of the weldshown in Fig. 7 takenin connection with the plan views; the members being in the form ofsmall plates of about the same thickness as the tube wall, of a lengthabout equal to their width or slightly less and of a spacing about equalto their thickness or less.

A -suitable machine and method 'for applying projections to the tubesare described in application Ser. No. 589347, filed by Hoffer, January28, 1932.

Electric resistance welding Operations of this type are important inorder to produce a continuous homogeneous metalic path for conductingthe heat from the projection to the tube; that is, a path in which thereis no interruption of the continuity and homogeneity of the conductingmetal. At the same time resistance welding operations pass the currentthrough the parts to be welded and heat them to a considerable degree.It is this heating of the metal of the tube particularly which sets upthe strains referred to hereinabove, and it is for units made by thisparticular welding method that the present invention has its greatestadvantage.

Not only is the tube apt to be distorted by the welding temperature, butalso the projection. such distortion, or tendency to distort, sets upinternal strains in the projections. Metal under such internal strain ismore readily oxidized than metal in which there is no such strain.

With the comparatively smallcross-section projections illustratedherein, there are no substantial internal strains set up. consequently,they may be made to extend to a much greater width or radial distancefrom the tubes than where flanges or projections are used of such a sizeas to be internally strained during the welding operation.

In the present invention the radial dimension of the projections may bedetermined in advance on the assumption that the metal is not strainedsubstantially and the ends of these projections may be extended to aconsiderable distance and still be proo f against burning away; thoughwith a continuous fiange of any substantial length in the axial'direction they would not be so.

With the continuous fins of the prior patente, the strains induced bythe welding operation have been so great that it has not been safe tocut away any. portion of a fin at one side only of a tube because of thestrains on the other side. Nevertheless openings through the ns aredesirable for peep holes, air passages or the like. This disadvantage isobviated by the present invention.

With the use of separate projections, as in the present unit, one ormore of these may be omitted at one side without danger of injury orexcessive distortion arising from the provision of projections on theopposite side.

Various modifications may be made by those skilled in the art withoutdeparting from the invention as dened in the following claims.

- What is claimed is:

1. A tubular unit of the character described adapted to be exposedexternally to high temperatures and to carry a liquid to be heated,constituting a complete unitary article of manufacture and consisting ofalong steel tube of small diameter Compared with its length and of smallwall thickness Compared with its diameter and separately formed fiangemembers each of which is of less length than the tube and has a freeouter edge and each of which is separately welded at its nner edge tosaid tube, said fiange members being in longitudinal alinement with eachother parallel with the axis of the tube and being separated from oneanother by short intervals.

2. A tubular unit of the character described adapted to be exposedexternally to high temperatures and to carry a liquid to be heated,constiiuting a complete unitary article of manufacture and consisting ofa long steel tube of small diameter Compared with its length and ofsmall wall thickness compared with its diameter and separately formedfiange members each of which is of less length than the tube and has' afree outer edge and each of which is separately welded at its inner edgeto said tube, said 'flange members being separated from one another byshort intervals, the thickness of the welded unit at the root of thefiange being greater than at the ou er edge of the fiange.

3. A'tubular unit of the character described adapted to be exposed tohigh temperatures and to carry a fluid to be heated, constitu' ing acomplete unitary article of manufacture and consisting of a long steeltube of small diameter compared with its length and of small wallthickness compared with its diameter, and a line of separately formedprojecting members each of which is of comparatively short length andhas a free outer edge and each of which is separately welded at itsinner edge to said tube. said projecting members being separated fromone another by short intervals so that the line of such members -formsan interrupted fiange on the ou' side of the tube.

4. A tubular unit of the character described adapted to be exposed tohigh temperatures and to carry a fluid to be heated, constituting acomplete uni ary article of manufacture and consisting of a long steeltube of small diameter compared with its length and of small wallthickness Compared with its diameter, and projecting members composed ofseparate small plates of about the same thickness as the tube wall, of awidth less than the diameter of the tube and of a length (in the generaldirection of the length of the tube) about equal to their width, each ofsaid members being separately welded to said tube.

5. A tubular unit of the character described adapted to be 'exposed tohigh *Zemperatures and to carry a fluid to be heated, coistituting acomplete unitary article of manufacture and consisting of a long steeltube of small diameter compared with its length and of small Wallthickness Compared with its diameter, and projecting members composed ofseparate small plates of about the same thickness as the tube Wall, of awidth less than the diameter of the tube and of a lengh (in the generaldirection of the length of the 'Lube) about equal to their width, eachof said members being separatcly welded to said tube, said members beingseparated at their welded edges by a distance about equal to theirthickness or less.

6. A tubular unit of the character described adapted to be exposedexternaily to high temperatures and-to carry a. liquid to be heated,consisting of a long steel tube of small diameter compared to its lengthand of small wall thickness compared to its diameter and a plurality ofheatconducting extension members welded to the out-.

7. For a water wall exposed to radiant heat at a side of a combustionchamber, a tube provided with a series of separate longitudinallyextending and aligned fin-like projections Secured thereto at oppositesides thereof, the ends of said sections being spaced slightly from eachother to com- 'A.-tube for the heating and crculatng of pensate forirregularities in' expansion and contraction in portions of saidsections adjacent to the tube as compared with portions thereof remotefrom the tube, but said sections being disposed in suicient proximity toeach other, lengthwise of the tube, to provide a subs' antially unbrokenfurnace chamber wall. i

8. A water tube of the character described having a series of separatelongitudinally extending and aligned fin-like projections securedthereto, the ends of said sections being slightly spaced from each otherto provide for irregularities in expansion and contraction of saidprojections in portions thereof remote from the tube as compared withportions thereof adjacent to the tube, but said projections being ner asto provide a substantialiy unbroken furnace chamber wall when used incombination with other similarly arranged tubes.

4 I water o'r other fluid, said tube having a series of numerousseparate projections orming extended heating' surfaces, each beingunited directly to said tube by a separate electric resistance weldproviding a continuous homogeneous metallic path for conducting heat,each weld having an area small enough to permit application of theprojection without substantial strain upon or deformation of the tubeand the projection by the welding operation or under subsequent exposureto high temperatures and the projections being applied oversubstantially the entire exposed length of the tube and having theirouter ends tree o that they can expand separately under heat, wherebythe unit is adapted to stand exposure to high temperatures withoutinjury and the projections at ends remote from the tube.

10. In a boiler wall constru'ction, 'a multiplicity of upright tubesconnected into the circulation of the boiler'spaced apart from oneanother and connected at their ends, and metallic members extendingsubstantially across the' spaces between said tubes and consisting ineach space of a series of comparatively small members sepa rate fromeach other in heat conducting engagement with the tubes and slightlyspaced apart so that they can expand separately under heat.

- 11. The combination of a plurality of heat conducting units forboilers, each unit comprising a long small-diameter thin-walled steelboiler tube, each having at least one longitudinally extending series ofsmall projections separate from each disposed in such manare proofagainst burning away r other and welded to' the tube with their outeredges free.

12. Atubetor the heating and circulating ot water or other fluid, saidtube having a series of separate projections on its exterio'r formingextended heating'surfaces, each projection having a width (transverse tothe tube axis) which is at least as great as its length (parallel to theaxis) 'at its tube-engaging end, each projection being united directlyto the tube by a separate electric resistance weld providing acontinuous homogeneo'us metallic path for conducting heat, each weldhaving an area small enough to permit application of the projectionwithout substantial strain upon or deformation of the tube and theprojection by the welding operation or under subsequent exposure to hightemperatures and the projections being applied over substantially theentire exposed length of the tube and having their ends free so thatthey can expand separately under heat,

whereby the unit is adapted to stand exposure to high temperatureswithout injury and the projections are proof against burning away atends quent exposure to high temperatures and the projections beingapplied over substantially the entire exposed lengthof the tube andhaving their outer ends free so that they can expand separately underheat, said projections being spaced as closely to each' other as ispracticable without interference when heated, whereby the -unit isadapted to stand exposure to high temperatures without injury and theprojections are proof against burning away at ends remote from the tube.

14. The tube o'f claim 9, the projections being parallel with each otherand the series of projections being in a line parallel to the axis ofthe tube.

15. The tube of claim 9, the projections being of approximatelyrectangular cross-section with their faces extending lengthwise of thetube.

16. A *tubular unit of the character described adapted to be exposedexternally to high temperatures and to form part of the circulatingsystem of a boiler, constituting a complete unitary article ofmanufacture and consisting of a long steel tube o'f small diametercompared with its length and of small wall thickness compared with itsdiameter and separately formed outward projections, separately welded attheir inner ends to the tube and separated from one another by shortintervals, said projections having a width (transverse to' the tubeaxis) which is at least as great as half the diameter of the tube, theouter ends of the projections being free so that they may expandseparately under heat and the welded area being so proportioned to thewidth as to avoid introducing substantial internal strains o'n the tubeand projection and to sufce for transferring to the tube the heatabsorbing capacity of the projection. a v

17. A tube for the heating and circulating of water or other fluid, saidtube having a smooth interier for unobstructed circulation of the waterand having numerous separate projections on its exterior formingextended heating surfaces, said projections being spaced as closely toeach other as is practicable without interference when heated andexpa'nded, so' as to provide a substantially unbroken wall.

18. A tube for the heating and circulating of water or other fluid, saidtube having numerous separate projections on its exterior tormingextended heating surfaces, said projections having small ende welded tothe tube 's as to avoid the occurrence of substantial strains from thetube and projections and said projections being spaced as closely toeach other as is practicable without interference when heated andexpanded, so as to 5 provide a substantilly unbroken wall. JOHN F.MURRAY, JOSEPH B. MURRAY, 'I'HOMAS E. MURRAY, JR.,

Ezecutors for the Estate of Thomas E. Murray, o

Deceased.

